Microsoft will provide feature and functionality updates and upgrades to Windows 10 for a full 10 years from the time the OS is purchased -- as part of a new device, for example -- an analyst briefed by the company said Tuesday.

"Microsoft's intention is that you will get 10 years minimum of updates for Windows 10, both feature and security updates, from when you get it," said Steve Kleynhans, a Gartner analyst who tracks the Redmond, Wash. firm [emphasis added].

Kleynhans, who had long pressed Microsoft for clarification on its vague statements about Windows 10 support, was paraphrasing from an email Microsoft sent Tuesday after he had again queried the company. He declined to share the exact contents of the email with Computerworld.

"They intend to provide the full 10 years of support, which means giving feature and security updates for that computer for 10 years, provided the OEM [original equipment manufacturer] continues to support the device," Kleynhans added. "If something happens, say you have a device with a 16GB SSD [solid-state drive] and suddenly at some point they can't fit Windows 10 on a 16GB SSD, sorry, you're out of luck. They'll support [Windows 10] until the hardware physically can't handle it." Or until the decade expires, whichever comes first.

The crucial part of Microsoft's plan: The clock starts when the customer first starts using Windows 10. "If I bought a new PC four years from now, I will get 10 years from that point," said Kleynhans.

That's a huge change from Microsoft's current support policy. Since 2002, Microsoft has promised to support each Windows edition -- Windows XP, Windows 7, Windows 8 -- for 10 years, but the start time began when Microsoft released the product, not when the customer acquired it. And Microsoft set exact deadlines when support expired.

Windows 7's support, for example, will end in January 2020, 10 years and a few months after its October 2009 debut. But new Windows 7-equipped PCs purchased today -- computer makers still sell them -- will receive updates, solely security updates at this point, only for the next four-and-a-half years.

Kleynhans did not outline how Microsoft will keep track of Windows 10's support decade, but one possibility is the product activation date of the OS; another is to track the date when the user first logged onto the machine with Microsoft Account credentials.

On Friday, Microsoft amended its support lifecycle fact sheet -- a page that lists how long updates will be provided for each edition of Windows -- to include the new OS, which launches next week. On the fact sheet, Microsoft listed Windows 10 in the traditional "Mainstream" and "Extended" five-year stretches.

Historically, Microsoft has offered both security and bug fixes in Mainstream but only security updates in Extended. Because it slotted Windows 10 into the two periods, and because the company hedged in its description of what the OS was to receive when -- the sheet noted, "Updates may include new features, fixes (security and/or non-security), or a combination of both" [emphasis added] -- the support policy could be interpreted as offering feature/functionality changes and upgrades for only the first five years under Mainstream support. (Security-related updates would be delivered throughout the decade.)

Microsoft seemed to say that in a reply to Computerworld's questions on Monday about whether it would deliver new features and other changes for only five years, or for the full decade lifecycle of Windows 10.

"Examples of non-security updates could include new features and capabilities, or driver and firmware updates for a better customer experience when using Windows 10," a spokeswoman said in an email. She also pointed to a graphic on this lifecycle support page that showed non-security updates available only during mainstream.

So, was Microsoft sticking with the usual support for Windows 10 or not? Would it introduce new features and capabilities only for 5 years, not 10?

Those questions were important: Microsoft had repeatedly trumpeted Windows 10 as different, radically so, from predecessors, and had cast it with the phrase "Windows as a service" to describe its constant evolution. "This changes the rules of the game," said Terry Myerson, chief of the Windows group, in February of Windows 10.

But a strict Mainstream + Extended support policy was nothing but old-school. If Windows 10 adhered to it, what was new about the OS's approach?

"That is very specific to the LTSB [Long-term Servicing Branch]," said Kleynhans of the 5 + 5, Mainstream + Extended policy outlined by Microsoft on Friday. "There are very specific things built around that."

LTSB is one of four update tracks -- Microsoft calls them "branches" -- that determine when a customer receives updates and upgrades. It will be available only to organizations with volume licensing deals for Windows 10 Enterprise, and requires the extra-expense Software Assurance program as well. Unlike other branches, LTSB treats Windows in the old style, serving PCs on that branch only security patches and critical bug fixes, but not pushing new features or other changes to the devices.

"This new Windows-as-a-service model ... I think Microsoft is having difficulty taking its older [support policy] language and reworking it to fit their new model," said Kleynhans as he tried to explain the disconnect between what the lifecycle fact sheet showed and what Microsoft had told him.

"When they talk about changing the servicing model for the OS, moving it forward, keeping it updated, they are rethinking the whole process," Kleynhans added. "I'm not convinced they have all the kinks worked out, but we do see the intention of where they want to go.

"It's significantly different than what we've had in the past," he concluded. "It may take a few years for everyone to settle into this and really feel how different is it."